That isn't exactly a shining example of "providing more information".
You seem to be asking a question about web applications, based on your mention of "web.xml". It would be helpful if you said so, instead of making us guess. But then you asked about a "java program", which doesn't apply in the context of web applications. And then there's that good old buzzword "dynamically" which usually only means "at run time" but can mean other things. So you need to be more specific.